Catheters are well known for use with the human body as part of diagnostic or treatment procedures. Such devices are typically introduced through body lumens such as blood vessels and are advanced to the sight designated for diagnosis or treatment, which sight may be a particular vessel or organ. For example, it is well known in percutaneous transluminal coronary angioplasty (PTCA) procedures to introduce a small diameter catheter into a stenosis portion of a blood vessel caused by arteriosclerosis or the like. The PTCA procedure typically includes inserting such a catheter equipped with a dilator such as a balloon at its tip into the stenosis portion of the blood vessel and inflating the dilator so as to dilate the stenosis portion of the blood vessel, thereby improving blood flow at the distal side thereof.
During such PTCA procedures, a guidewire is typically first introduced into the blood vessel and positioned within the blood vessel at the area of the stenosis portion. The catheter equipped with the dilator is then inserted over the guidewire and advanced through the blood vessel to the area of treatment, for carrying out the necessary procedure. After dilation of the stenosis portion of the blood vessel, often times a vascular stent is implanted into the blood vessel in order to maintain the blood vessel in an open position.
Catheters and guidewires are supplied in a variety of sizes and diameters. Specific applications and procedures typically involve use of specific size catheters and guidewires. For example, due to the tortuous path of blood vessels in cardiology procedures, cardiologists typically prefer smaller diameter guidewires such as a 0.018 inch diameter catheter, since they include features which are amenable to such uses, including flexibility. On the other hand, radiologists may prefer to use a larger diameter catheter, such as a 0.035 inch catheter, for cost and ease of use for a particular application.
It is common place for end users such as physicians carrying out catheterization procedures to become accustomed to using one particular size guidewire in such procedures. Such a physician would therefore be reluctant to incorporate catheter systems which require use of a different size guidewire. For example, while a physician typically may prefer to use a 0.018 inch guidewire due to specific characteristics including tip transition, column strength, pushability, trackability and tensile strength, catheters systems which are designed for use with a different size guidewire, such as a 0.035 inch guidewire, are becoming more common place, for example, in percutaneous catheterization procedures, and specifically for those procedures involving delivery and employment of peripheral stents.
Accordingly, it is desirable to provide for the use of a smaller diameter guidewire with a larger diameter dilatation catheter.